On existing aircraft, turbofan engines such as turbo-jet engines are suspended below the wing by complex mounting devices, also known as “EMSs” (Engine Mounting Structures), or even engine strut. The mounting devices commonly used have a rigid structure forming a box, i.e. formed by the assembly of lower and upper and spars interconnected by a plurality of transversal ribs located inside the box. The spars are arranged in lower and upper faces, whereas the sidewall panels close the lateral faces of the box.
In a known manner, the rigid structure of these struts, also referred to as the primary structure, is designed to allow static and dynamic forces generated by engines to be transmitted to the wing, such as the weight, thrust, or the various dynamic forces.
In this regard, in the engine struts known from the prior art, the transmission of forces between the latter and the wing is conventionally ensured by a set of mounts including a forward mount, a rear mount and an intermediate mount, notably designed to transmit the thrust loads generated by the engine.
To do this, the intermediate mount designed to transmit the thrust loads, also known as “spigot” mount, is generally implemented by a ball joint secured in the rear upper spar of the rigid structure, between the forward mount and the rear mount. This spigot mount also comprises a shaft or a shear pin secured beneath the wing of the aircraft via a mounting fitting, so as to be housed in the ball joint. The mounting fitting is generally secured to a lower portion of the wing box, usually the lower wing box spar.
On recent turbofan engines, the high bypass ratio sought leads to extremely high congestion, as an increase in the bypass ratio inevitably results in an increase in the diameter of the engine, and more particularly an increase in the diameter of its fan casing.
Also, with a ground clearance established so as to remain acceptable from a safety point of view, the space remaining between the wing element and the engine is becoming increasingly restricted, even nonexistent for engines with high bypass ratio engines. Therefore, it may be difficult to implement the engine strut and the various wing mounts in this remaining vertical space, usually dedicated to this location.
The development of turbofan engines has thus had the unfortunate consequence of imposing a reduction in the vertical dimensions of the engine strut, notably so as to maintain sufficient space to place the mounting fitting of the intermediate mount, whose main dimensions are imposed by the need to transmit thrust loads of the engine, i.e. loads oriented in the longitudinal direction of this turbo-engine, as well as those oriented in the transversal direction thereof. As an indication, it is recalled that the longitudinal direction of the turbo-engine corresponds to the direction of the main axis of rotation of the propulsion system.
However, the possibilities of reducing the vertical dimensions of the engine strut are limited. The rigid structure of this strut, also referred to as the primary structure, must be of sufficient dimensions to have the mechanical strength capable of withstanding the transmission of forces from the engine to the wing element, with low deformation under load so as not to degrade the aerodynamic performance of the propulsion system.
In the prior art, numerous solutions have been proposed to bring the engine closer to the wing element to which it is suspended, and in order to maintain the required ground clearance. However, as the diameters of the fan casings are increasingly large in order to meet bypass ratio requirements, these solutions must be further optimized.